The present invention provides a waste treatment process and device thereof which can reduce the size and weight of organic waste by decomposing the waste to powder form and bacteria free substance that may be used as a kind of fertilizer for plants. The waste is first frozen by liquefied nitrogen in a cooling chamber to a temperature less than -200 DEG F., wherein during this freezing procedure, the gas generated from the waste must be removed from the cooling chamber. Then, the frozen nitrogen is immediately transferred to a heated chamber having a temperature of at least 160 DEG F. but not exceed 200 DEG F. During this heating procedure, the water content of the waste is sucked out of the heated chamber, so that the waste is decomposed to form the bacteria free powder.
